JDBC Connection

Hello

    I am trying to connect to PostgreSQL from Java (JDK 1.1.6) under RedHat
Linux 5.1 using the JDBC interface. I have compiled the driver and tried to
run the examples this way:

java -Djdbc.drivers=postgresql.Driver example.basic jdbc:postgresql:prueba
postgres postgres

where 'prueba' is the name of an existing database.
But I always get a 'Connection refused' error in
DriverManager.getConnection("jdbc:postgresql:prueba")

I have modified pg_hba.conf to allow any user on any host access to any
database
but the error still remains.

Can anybody tell me what can be the problem and any possible solution?

                    Thank you very much